DESPERATE times call for desperate measures. Why not tackle global warming with a giant dust cloud positioned in space to block out the sun?
The sun shield – made from dust mined from the moon – is the brainchild of Curtis Struck at Iowa State University in Ames and would be used only if governments fail to tackle the greenhouse effect.
Lunar dust particles are just the right size to scatter sunlight, Struck says. If the particles are injected at two precise positions along the moon’s orbit, they will form a pair of stable clouds that would each pass in front of the sun once a month, blocking sunlight for about 20 hours each month (Journal of the British Interplanetary Society, vol 60, p 1).
“If we’re facing real threats to civilisation, then you might resort to this sort of thing,” says Struck. Others have criticised the scheme on the grounds that the clouds may reflect extra light onto Earth during the periods when they are not directly in front of the sun. Struck maintains that even if this happened, there would still be an overall decrease in the sunlight reaching Earth.